Introduction. 



The Scope of Comparative Anatomy. 



§ I- 



The department of science which has organic nature for the object 

 of its investigations, breaks up into two great divisions, Botany and 

 Zoology, corresponding to the two kingdoms of organised nature. 

 The two disciplines together form the science of living nature — 

 Biology. They are closely connected with one another, in so far as 

 the phasnomena seen in both the animal and vegetable kingdoms 

 rest on the same fundamental laws, and in so far as, notwithstand- 

 ing the differences of their special arrangements, animals and plants 

 have common beginnings, and are, in the economy of nature, closely 

 interdependent. 



In both of these disciplines several kinds of investigation are 

 possible, and from these new disciplines arise. Putting aside the 

 realm of Botany, let us follow out that of Zoology into its further 

 subdivisions. The investigation of the functions of the animal 

 body, or of its parts, the reduction of these functions to elementary 

 processes, and the explanation of them by general laws, is the busi- 

 ness of Physiology. The investigation of the material substratum 

 of those functions, and accordingly of the phasnomena of form of 

 the body and its parts, as well as the explanation of the phasnomena 

 of form by reference to function, is the business of Morphology. 

 Physiology and Morphology have thus different duties, and their 

 methods also are different ; but for each it is necessary, although in 

 different ways, to keep in view the other, as well as the common 

 aim, which is indicated in the term Biology. 



Morphology again is divided into Anatomy and Embryology; 

 while the former has for the object of its investigations the adult 

 organism, the latter has the growing organism as the object of its 

 study. 



B 



